The effects of carbon addition on thermal stability and hardness ofZr41Ti14Cu12.5Ni10Be22.5bulk amorphous alloy were investigated. It is found that a small amount of carbon addition further extends the supercooled liquid range and enhances the thermal stability and strength of the alloy. More carbon addition results in the formation of a crystalline and amorphous mixture accompanied by a pronounced increase in microhardness. The effects of the carbon addition on the amorphous alloy are discussed from the structural point of view. ©1997 American Institute of Physics.